The concept of heart failure is basic in the daily practice of clinical medicine and in contemporary physiology and pathology. Almost nothing is known of how this concept originated. From Galenic times a doctrine of humoral excess and humoral depravation was inherited. Carolus Piso (1618) wrote of localized accumulations of fluid. For a long time thereafter, no relation was suspected between such accumulations and inadequate cardiac function. Our present concept was almost fully developed by the middle of the nineteenth century. Between these temporal limits lie the obscure historical developments that are now being explored.